Hilfe Wahrheitstabelle (Digitaltechnik)?

The number Column for your Input variables is also the number of input variables. You have a, b and c as input variables, so you need 3 columns for the inputs.

You also have an output x, which is then the fourth column. You don’t need more columns for a truth table first!

The number rows depends on the number of inputs.

That is, in your case you need 2^3 = 8 lines.

You can prefill the cells for the inputs. Start with the first column. Fill half of the rows of this column with a zero, the other half with a 1, see below.

a | b | c | x
-------------
0 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |

The neighboring columns for b are now treated, but do not change the number after 4, but after 2 lines.

a | b | c | x
-------------
0 | 0 |
0 | 0 |
0 | 1 |
0 | 1 |
1 | 0 |
1 | 0 |
1 | 1 |
1 | 1 |

The column c is also the same, only that you change the number after each line.

a | b | c | x
-------------
0 | 0 | 0 |
0 | 0 | 1 |
0 | 1 | 0 |
0 | 1 | 1 |
1 | 0 | 0 |
1 | 0 | 1 |
1 | 1 | 0 |
1 | 1 | 1 |

The pattern should be clear now. If you look closely at the last table, you can see that you don’t make anything further than counting high starting from zero, in binary numbers.
This structure applies to both circuits because both have 3 inputs. Your table does not refer to a gate of a circuit, but to the entire circuit!

Now look at the state (x) for a circuit for each line. If, for example, the output (x) is at line 1 (where a=0, b=0 and c=0) to 1, then you write into the first line for x is 1 pure, otherwise a zero.